This invention relates to construction systems using concrete panels.
Concrete panel systems have been used primarily to provide pre-manufactured walls for residential or small commercial or industrial buildings. Such systems promise a more accurate building, reduced on-site building time and waste, insect resistance and a hedge against rising lumber prices.
U.S. Pat. No. 3,475,529 describes a method of making a prestressed hollow core concrete panel. A first section is formed comprising a slab having a flat outer face and a plurality of ribs extending from an inner face. This first section is then laid ribs down on a second section, which is either a flat slab or a duplicate of the first section laid ribs up. The two sections are joined together. In an embodiment, the cores of the panel are closed.
U.S. Pat. No. 3,683,578 describes a concrete panel building system in which the panels have an inner insulating layer sandwiched between concrete layers. The space between the concrete layers cooperates with a guide nailed to a foundation to align the wall panels on the foundation. Upper portions of adjacent wall panels are secured together by a various bolted connections.
U.S. Pat. Nos. 4,605,529, 4,751,803 and 4,934,121 describe concrete wall panels having vertical ribs extending between horizontal upper and lower beams all attached to a concrete slab which provides the outer surface of the wall. The ribs and beams of the panels are reinforced by longitudinal reinforcing bars and the concrete slab is reinforced by a wire mesh. A xe2x80x9cbolting saddlexe2x80x9d cast into the ends of the upper beams allows adjacent panels to be bolted together. U.S. Pat. No. 5,656,194 describes an improved assembly jig having hinged sidewalls for use in making such panels.
U.S. Pat. No. 5,493,838 describes a method of constructing a basement from prefabricated concrete panels. The building site is first excavated and footings are positioned in the excavation to define the outline of the building. The footings have a groove in their upper surface to accept wall sections which comprise a slab having a flat outer face and a plurality of ribs on an inner face. Freestanding comer wall sections are placed first on the footings. Flat wall panels are then joined end-to-end between the comer sections to complete a peripheral wall. A conventional wooden floor deck is constructed over the peripheral wall to strengthen the structure before the basement is backfilled.
It is an object of the present invention to improve on the prior art. This object is met by the combination of features, steps or both found in the independent claims, the dependent claims disclosing further advantageous embodiments of the invention. The following summary may not describe all necessary features of the invention which may reside in a sub-combination of the following features or in a combination with features described in other parts of this document.
In various aspects, the invention provides a concrete building panel having a slab and a plurality of ribs and beams. The ribs include interior ribs and end ribs which are generally perpendicular to the slab and oriented vertically in an installed panel. The beams include an upper and lower beam which are generally perpendicular to the slab and oriented horizontally in an installed panel.
The spacing of the ribs is determined in view if a fraction of the length or width of common sheet materials, the fraction having a numerator of 1 and a whole number denominator. A series of horizontal holes in the ribs are spaced at a selected constant spacing such that adjacent panels may be fastened together through them. Adjacent wall panels may be mounted with their bottom surfaces at different elevations, the elevations differing by the selected constant spacing.
A rabbet in the upper surface of the panel opens to the outside face of the panel to receive the exterior sheathing or finish material of a second wall panel mounted above the first wall panel. The second wall panel has an extension extending from its bottom surface into the rabbet of the lower wall panel. A smaller rabbet around some or all of the perimeter of the panel opens towards an outside face of the panel to receive water infitration resisting material.
In one type of panel, the slab is separated from the ribs to provide an air gap. Reinforcing bar segments forming a series of at least partial triangles extend from the ribs to the slab to secure the slab in position relative to the ribs. Insulating blocks capable of resisting a compressive load are also provided between the slab and the ribs. The insulating blocks extend beyond the edges of the ribs to provide a surface for attaching sheet material between the ribs to close off the air gap.
Connections between holes in two adjacent concrete wall panels are made by a hollow conduit having an abutment at either end to engage the concrete wall panels. The abutments do not substantially block openings at the ends of the hollow conduit permitting materials to pass through the conduit. Preferably, the abutment on at least one end of the conduit is a nut threaded onto the conduit.
Other connections between adjacent panels involve horizontal channels in the exterior faces of the beams which extend from an edge of the panel to a hole through the beam. The horizontal channels of adjacent panels form a continuous channel. A stitch has a member which fits into the horizontal channels of two adjacent panels and legs which extend through the holes of the beams. The legs are adapted to receive a fastener to secure the stitch.
Other connections between adjacent panels involve vertical channels in the end ribs. The vertical channels of horizontally adjacent panels form a space. A plate is fitted into the space to provide an interference fit with the vertical channels to align the adjacent panels relative to each other. In some cases, the plate extends upwards into the space of a second pair of horizontally adjacent panels mounted on top of the first pair of horizontally adjacent panels.
Load bearing horizontal holes through the ribs are reinforced with reinforcing bar in the concrete arranged in generally triangular shapes. The load bearing holes and reinforcement are located such that apexes of the triangularly shaped reinforcement are located between the perimeter of the hole and the distal edge of the rib relative to the slab.
The concrete panels are made by providing a form having base and sides which define the perimeter of the panel and sub-forms which define the spaces between the ribs. At least two sets of holes are made through the two opposed sides of the form and through two opposed sides of each sub-form. Each set of holes is concentric when the sub-forms are properly positioned in the form. The sub-forms are positioned in the form at least in part by placing rods through each set of concentric holes. Concrete is poured into the form to form the slab and the ribs. The rods are sized to produce holes in the ribs to accept the conduit connectors referred to above. The reinforcing bar is pre-assembled into a basket comprising wire mesh for the slab and trusses for the ribs.